It's not too often you bring in a player that can make an instant impact for your team - so when it does happen, its usually worth a mention.
Here, GMS contributor Lewis Buckley gives his take on those who have recently joined new clubs and look set to prove themselves brilliant pieces of business.
Let's start off with the obvious way to tell if someone is having a good game - by scoring.
Trinidadian international Kenwyne Jones was recently involved in a swap deal between Stoke and his new club Cardiff, seeing Nigerian striker Peter Odemwingie head the other way after only six months in Wales.
It was slightly controversial on Jones' part as he simply didn't want to play for the Potters in a home game against Liverpool. Although he later cited it was for "personal problems" he notified manager Mark Hughes of this by text - eventually receiving a two-week fine for his non-appearance. This had no effect on his first performance for the Bluebirds though as he went to play the whole 90 minutes for his new team, scoring the winner against Norwich in the league and contributing an overall impressive performance.
While on the subject of first game for Cardiff, I can not neglect to mention Manchester United loanee Wilfied Zaha. Playing a man of the match performance with a fine assist for the equaliser and generally the most threatening looking force on the pitch, Zaha can blossom under Ole Gunnar Solskjær and become a top-class winger if he repeats the form he showcased during his first game and carries on developing as a player.
Moving on to one of the big purchases, or should I say re-purchases, Nemanja Matić, being brought back to Chelsea for £21million after leaving the Bridge three years before in a swap deal for David Luiz - has already justified his price tag.
Although not technically his debut, Matić played his first full 90 minutes in the league away to Manchester City on Monday in a match that provided the top-quality you'd expect. His only minutes on the pitch before hand for the Blues were in an FA Cup tie against Stoke and only a collective 33 minutes in the league, but you wouldn't think it given his performance against the former league leaders.
With perfect positioning for interceptions, the ball-winning of a top tackler and the retention and distribution of a deep-lying playmaker (86% pass success in the league so far) he really was in control, dictating the play from midfield.
Elsewhere in Europe it was a dream return for Brazilian midfield maestro Diego to his former loan club Atlético Madrid. Spending a season in the Spanish capital on loan from German club Wolfsburg in 2011-12, he established himself as an important figure and fan-favourite by regularly performing to a high level and helping them towards lifting the Europa League trophy.
Now back for good, he made a permanent transfer to Madrid for a bargain-price of roughly £1.3million - marking his debut with a top, selfless performance and a goal in a 4-0 thrashing of Real Sociedad.
Although slightly less sunnier than Spain - Scotland also had a new face to be proud of. Celtic's new Norwegian midfielder Stefan Johansen was brought in from Strømsgodset, a team in his homeland, as a backup/first team bordering player who could come onto the pitch and find his team with his passing prowess for an estimated £2million.
He did a lot more on his debut for the Bhoys than anyone would have expected, manipulating what went on in midfield and never wasting a pass - he was the lynchpin and reliable source for a full 90 minutes earning a specific point-out and praise from his manager Neil Lennon.
As well as the top division having players that all marked their debuts with memorable performances, there were also the few that arrived in style to their new clubs in a lower league too; the Championship, which saw multiple score in their first match all in the same weekend.
There were the loanees such as Manchester United's young striker Federico Macheda and West Ham's Modibo Maïga who both scored important equalisers for their new teams, also the likes of Kevin Doyle on loan from Wolverhampton and Nottingham Forest's new purchase Rafik Djebbour who shone in their debuts, both scoring and performing impressively.
We are yet to see the emergence of some players - with the likes of Arsenal's Kim Källström, Crystal Palace trio Tom Ince, Scott Dann and Joe Ledley, Everton's Lacina Traoré, Fulham's Kostas Mitroglou, Lewis Holtby and Johnny Heitinga, Sunderland's Ignacio Scocco amongst others still to make their debut for the new club. Keep your eyes open for more potentially memorable first-time appearances.
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